Ruby: Do not attempt to track precise hash indices for floats and complex numbers

[hvitved]

As pointed out by @asgerf, the inherent imprecision when comparing floats (and complex numbers) makes them unsuitable for tracking precise hash index information. We therefore simply treat reads and stores with float/complex indices as unknown indices.

[asgerf]

I think we should also restrict it in TKnownPairValueContent

[hvitved]

I think we should also restrict it in TKnownPairValueContent

Right, I'll fix.